1/(1+√2) = (√2–1)/((√2–1)(√2+1)) = (√2–1)/(2–1) = √2–1,
1/(√2+√3) = (√3–√2)/((√3–√2)(√3+√2)) = (√3;–√2)/(3–2) = √3–√2,
. .
1/(√2004+√2005) = (√2005–√2004)/((√2005–√2004)(√2005+√2004)) = (√2005–√2004)/(2005–2004) = √2005–√2004.
<span>Сумма равна √2–1+√3–√2+…+√2005–√2004 = √2005–1.</span>
1)y=9x^2-3x+5 y'=18x-3
2)y=-2x^3+7x-1 y'=-6x^2+7
3)y=1/3x^12-2/7x-п y'=4x^11-2/7
1) 3х-5=3×3-5=4
3×0-5= -5
3×(-1)-5=-3-5= -8
3×7/3-5=21/3-5=7-5=2
Пусть х ширина окантовки ,тогда площадь белой бумаги можно записать
(12+2х)(14+2х)=360
168+28х+24х+4х²=360
4х²+52х-192=0
х²+13х-48=0
D=169-192=361
x1=(-13+19)/2=3
X2=(-13-19)/2=-16 НЕ подходит
Ответ ширина окантовки 3 см